Exposure of personal to hazardous materials in the atmosphere has long been a serious problem in many industries. As our knowledge increases, it becomes increasingly apparent that a wide variety of hazardous substances are present in the air we breathe and constitute major occupational hazards in numerous industries.
To counter the effect of hazardous materials in the atmosphere, numerous attempts have been made to provide personal monitoring devices which will supply an indication as to the extent of exposure of individuals wearing the badges. One such device is the "Personal Monitoring Device, Or Dosimeter, For Measuring Exposure Of Personal To Organic Vapors", U.S. Pat. No. 4,040,805 issued to L. Nelms et al. This patent discloses a personal monitoring device which is calculated to meet the National Institute for Occupational Safety and Health requirements by providing an indication as to the amount of vinyl chloride that a person has been exposed to within a work establishment. This device provides a fairly reliable means to determine certain pollutants in the atmosphere so long as the material used to adsorb the pollutants for subsequent analysis is maintained free of material which will interfere with the analysis and affect the ability of the adsorbing material to function in accordance with a desired, predetermined reaction rate.
D. Braun, U.S. Pat. No. 3,950,980 for "Vapor Sampling Device" is another U.S. Patent which attempts to provide a monitoring means to determine constituents in an ambient gas mixture. This patent and Braun's U.S. Pat. No. 3,924,219 on "Gas Detector Device" teach the principle of a detector material which reacts with a component to be monitored in a predetermined fasion. The reaction is regulated by controlling the gas contact with the adsorbing material through the use of porous gas flow attenuating means and channels. This approach eliminates variances in the monitoring system caused by velocity and incident angle variations of the impinging gas with respect to the sensing material but it fails to compensate for materials such as Cl.sub.2 in the atmosphere which are not being measured but which affect the measurement of the substance of interest.
A still further example of prior art gas monitoring means may be found in R. Goldsmith U.S. Pat. No. 3,985,017 on "Gaseous Contaminate Dosimeter And Method" which uses techniques similar to those of the Braun devices in that a membrane controls flow of the gas toward an adsorber but, like all of the known prior art devices, it fails to overcome the problems resulting from atmospheric constituents which interfere with the adsorption rate of the detector material.